Banacast: A Fast Adaptive Application Layer Multicast Network for P2P Live Streaming Research on streaming media data distribution via Peer-to-peer (P2P) application layer multicast (ALM) network is popular these years. This paper presents an unstructured P2P overlay which is used in the Banacast system. It analyzes which architecture could be taken use of in the P2P live streamingsystem, how to speed up the progress of joining P2P network with some strategies and algorithms, how Banacast to build a stable ALM network by its fast adaptive diffuse algorithm and node evaluate method. Experimental results show that Banacast system is able to provide large-scale concurrent users the high-quality video streaming services with a relatively lower hardware and bandwidth resource.